Conventionally, the industrial robot is installed in various production factories of electric apparatus, machines, automobiles, and the like, as a conveyance robot for conveying objects and a work robot for machining objects.
The industrial robot takes on various forms according to its use, and it needs high mechanical rigidity and high servo rigidity to be operated under a high load condition without difficulty. Further, the robot needs to be operated over a wide range in some uses.
In order to ensure high mechanical rigidity of the robot, a robot is proposed wherein a parallel link structure is employed in each of an upper arm mechanism and a lower arm mechanism (Patent Document 1).
Further, another robot is proposed wherein the parallel link structure is employed in the lower arm mechanism and also the upper arm mechanism can be operated independently of the lower arm mechanism in order to ensure high mechanical rigidity while ensuring a wide operation range (Patent Document 2).
Additionally, another robot employing a ball screw for an arm drive mechanism is proposed (Patent Document 3). Generally, the ball screw can ensure high mechanical rigidity by properly setting its operation range. Thus, mechanical rigidity of the robot can be enhanced by employing the ball screw as the arm drive mechanism.